“If “gay rapper” is an oxymoron where you come from, how to get your head around the notion of a gay rapper performing in a sports bar? What in most cities might seem plausible only as some sort of Sacha Baron Cohen-style provocation is just another weeknight in the cultural Galapagos that is New Orleans. Sometime after midnight on the sweltering Thursday before Memorial Day, the giant plasma-screen TVs at the Sports Vue bar (which “proudly airs all major Pay Per View events from the world of Boxing and Ultimate Fighting”) were all switched off, and the bar’s backroom turned into a low-lit, low-ceilinged dance club, where more than 300 people awaited a return engagement by Big Freedia, who by day runs an interior-decoration business and who is, to fans of the New Orleans variant of hip-hop music known as “bounce,” a superstar.”